JPH0419345A - Cylinder block for internal combustion engine and manufacture thereof - Google Patents

Abstract

PURPOSE: To promote lightweight and improve the frictional characteristic of a contact surface with a piston by forming a sleeve constituting a partial cylinder inner surface with a thin metal plate provided with holes by means of punching, and covering the punching part with a layer being thermally formed by means of thermal spraying. CONSTITUTION: A perforated sleeve 16 to be inserted into respective cylinders of a cylinder block 10 of a multicylindered internal, combustion engine is manufactured by a steel plate of about 1 mm in thickness. The sleeve 16 is equipped with a punched part or thin piece 18 which is punched outward at an angle αof 45 deg. in the radial direction. Punching depth (t) of the thin piece 18 is made into about 3 mm, and the height (h) into 10 mm respectively, and further the thin piece 18 is formed into being shifted (angle β) aslant in direction of a cylinder axis 22. Then, the sleeve 16 is made into being roughened of its surface by means of sandblasting, and after thermal spraying, a porous coated film consisting of cast iron solidified as a ledeburite (eutectic mixture between austenite and cementite) is applied to it.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The invention relates to an alloy cylinder block for an internal combustion engine, as defined in the preamble of claim 1 . [0002]

[Conventional technology]

This type of cylinder block is known, for example, from Japanese Patent Application Laid-Open No. 56-6
This is shown in Publication No. 0841. The cylinder block manufacturing method disclosed in this publication involves placing a cast iron sleeve with a large number of holes into a mold in advance when manufacturing a cylinder block of light metal parts using the pressure die casting method. It is. This sleeve has a relatively large wall thickness and forms the inner surface of the cylinder with good wear resistance. The molten light metal that has entered the hole solidifies into a fluff-like member that forms part of the contact surface with the piston and improves the thermal conductivity of the cylinder block. [0003]

[Problem to be solved by the invention]

A first object of the present invention is to provide a cylinder block of the type described above, which is lightweight, has high thermal conductivity, and has improved frictional characteristics of the contact surface with the piston. A second object of the invention is to provide a method for manufacturing this cylinder block at low cost. [0004]

[Means to solve the problem]

A first object of the invention is to provide an entire cylinder block according to the characterizing part of claim 1, namely:
The sleeve, which is inserted into each cylinder one by one and forms part of the inner surface of the cylinder, is made of a thin metal plate with holes formed by punching. The present invention is solved by providing a cylinder block for an internal combustion engine, characterized in that it is covered with a thermally formed layer. [0005]

[Effect]

According to the invention, the sleeve is constructed in the form of a mesh or lattice, which is tightly embedded in the base material during casting, especially in the pressure die-casting process. During punching to form a mesh or lattice, the cut-out sections are oriented as described in claim 2, so that the cut-out sections are completely anchored to the basic material of the cylinder block. Therefore, there is no "cylinder sleeve" in the conventional sense, as in the prior art described in the publication cited at the beginning, and the reinforcement material embedded in the base material itself is in contact with the piston. It forms part of the contact surface. [0006] The sleeve according to the present invention is preferably made of a steel plate as claimed in claim 4, and after manufacturing the punched portion, it is formed into a cylindrical shape, and the contact portion [000
7] The punchings, which can in principle have many geometric shapes (for example crater-shaped), are preferably constructed in the form of a lamella. This configuration is suitable for forming a coating film on the surface, and is also preferable from the viewpoint of ease of casting. In particular, the features of claims 6 to 8 propose a sleeve in which thin pieces having a wall thickness within a certain range and having the above-mentioned geometric shape are arranged. In this case, especially in the case of an in-line reciprocating internal combustion engine, although there are structural limitations, a very favorable cylinder inner surface structure can be obtained, particularly in terms of friction characteristics and workability (poling, honing). [0008] The coating formed thermally on the surface of the sleeve according to the present invention is obtained by powder coating using a tool steel powder having particularly good wear resistance as a carbide, nitride or boride.
can be formed. Furthermore, as described in the characteristic parts of claims 9 and 10, depending on what kind of force is applied to the inner surface of the cylinder (for example, whether it is a diesel cycle engine, an automatic cycle engine, a supercharged engine, etc.) Depending on the type of material used, the coating can be formed by solidifying the cast iron as leadebrite. Alternatively, if the inner surface of the cylinder is subjected to only relatively weak forces, it can be formed by a layer of hypereutectoid aluminum-silicon alloy. Moreover, as described in claim 11, it can also be formed of ceramic. Furthermore, depending on the case, it can also be formed by a plasma plating method using a wire or powder. This coating can have the desired porosity, allows reliable control of material consumption in the formation of the coating, is relatively low cost, and has excellent anti-friction and wear resistance properties. It is possible to form a coating film with [00091] Although gray cast iron alloy may be used as the base material or base material of the cylinder block in the case of engines that are subjected to large thermal stress, the sleeve according to the present invention is made of gray cast iron as a reinforcing material for the inner surface of the cylinder. It has also proven to be eminently suitable for cast cylinder blocks. In this case, if desired, the sleeve can only partially reinforce the inner surface, for example in the region of the piston ring at the top dead center of the piston against which the inner surface slides. [0010] Particularly suitable according to claim 13 has been found to be a coating formed by iron or steel in combination with iron oxide. This coating, which is particularly wear-resistant, can be produced satisfactorily by methods such as thermal spraying and can be produced with the desired porosity even in mass production. Porosity can be varied by parameters such as carrier gas (in the case of powder coatings) and distance from the nozzle. [0011] Further, it has been found that it is advantageous to mix a self-lubricating compound into the coating film according to the features of claims 14 to 16. These compounds significantly improve the warm-up behavior of the engine and, after warm-up, result in a guideway structure with recesses that retain lubricating oil. [0012]Finally, according to the features of claims 17 and 18, it is possible to apply as the last layer of the thermal coating a flux or an alloy with a high affinity for the base material, which is later applied inside the cylinder block. Ensures a tight bond of materials when casting the sleeve. [0013] The method problem of the invention is solved by the features of claim 19. Advantageous and suitable embodiments are evident from the following claims. The invention thus proposes that the sleeve, after being heat-coated, is placed in a mold for the cylinder block, aligned and directly cast. The purpose of this position adjustment is to prevent the sleeve, which is not very firmly fixed during casting, from shifting. [0014] Furthermore, when using a light metal, the silicon content is less than 14%,
In particular, it is proposed to use approximately 10% aluminum alloy, which facilitates the machining of the cylinder block. Moreover, the wear resistance and frictional properties of the cylinder surface are determined by the coated sleeve used. The present invention proposes to use a pressure die-casting method for casting the cylinder block. In this case, in addition to the known manufacturing advantages, there is the advantage that the sleeve joins the base material very tightly and with uniform contact pressure. [0015] It is highly preferable to brush the inner surface of the cylinder at the final stage of the process. During brush polishing, the soft part of the inner surface of the light metal cylinder is slightly depressed, thus creating an additional pocket on the contact surface with the piston to stabilize the position of the lubricating oil film. Therefore, even if a local overheating condition occurs, there is no need to supply a particularly large amount of lubricating oil to the load-bearing portion of the contact surface with the piston. [0016] When the contact surface with the piston has to meet particularly stringent conditions, gray cast iron can be used as the base material and/or after the casting and initial machining of the sleeve, but before the honing of the cylinder surface. It may be appropriate to melt, at least partially, to form a bond between the metals of the sleeve, the covering and the base material. Although cylinder surfaces of this type require correspondingly complex machining, they are suitable for very high demands with regard to their corrosion and wear resistance. A laser is particularly suitable as an energy source for the melting, with which surfaces can be melted even in the micrometer range with relatively small requirements. [0017]

【Example】

Embodiments of the invention will be described in more detail below. 1 and 5 partially show a cylinder block 10 of a liquid-cooled, multi-cylinder internal combustion engine with cooling channels numbered 12 and several cylinder inner surfaces 14. FIG. cylinder block 1
0 is manufactured by pressure die-casting from an aluminum-silicon alloy with a silicon content of 10%. [0018] A perforated sleeve 16 (FIGS. 2-4) is inserted into each cylinder of the cylinder block 10. The perforated sleeve 16 is manufactured from a steel plate with a wall thickness S of 1 mm. The sleeve 16 is provided with perforations or lamellas 18, which are perforated outwardly in the radial direction (line 20 in FIG. 3) at an angle α of 45°. The punching depth t of the thin piece 18 is approximately 3 mm, and the height h thereof is 10 mm. The laminae 18 are offset obliquely from one another in the direction of the cylinder axis 22. (angle β). [0019] The punching of the thin strips 18 is performed on a continuously supplied steel sheet strip. After punching, the steel plate strip is cut to a certain length. The cut-out sheet steel strip is bent into a tubular shape and spot-welded into a cylindrical closed sleeve 16 at a contact point 24 running obliquely to the cylinder axis 22 . [00201] The sleeve 16 is then sandblasted, roughened and, after thermal spraying, provided with a porous coating 30 of solidified cast iron as leadebrite. The coating film with a thickness of about 0.3 mm was made by flame spraying with a particle size of 0.3 mm.
This is carried out by supplying gray cast iron powder of 0.05 to 0.25 mm, which powder is sprayed in the melt state onto the cooled sleeve 16 in a known manner. The selected particle size controls the porosity of the coating. Rapid solidification results in a highly wear-resistant ledebrite layer. As shown in an enlarged view in FIG. 6, the porous coating 30 is molded to enclose the flake 18. Upon insertion of the sleeve 16, the lamina and the coating are bonded within the base material 10, but at the cylinder surface 14 (
after its mechanical processing) is exposed. [0021] Spacers 26, 28 are molded into the sleeve 16 (see FIG. 5) and are press die cast (not shown).
By positioning the sleeve 16 in .degree., a slightly conical (casting bevel) cylinder mold can be cast, as seen in FIG. At this time, the intermediate parts between the laminae 18 are filled with aluminum alloy, or the laminae 18 are embedded and fixed in the base material. The green casting is then machined, during which the cylinder is drilled and honed, in particular to create the cylinder face 14. The dimensions of the sleeve 16 are determined so that a portion of the sleeve 16 is exposed after poling and honing, and the hatched surface in FIG. 2 is the load-bearing portion of the contact surface with the piston. A coating film having excellent wear resistance is formed on a portion of this load-bearing portion, and a portion is bounded by this coating film. As shown in Figure 6,
These two parts alternate. [0022] The area demarcated by the coating film, ie, the area exposing the basic material, is slightly depressed and, as a final step, the cylinder surface 14 is brushed, at which time the surface is polished with a brush. Only non-hard basic materials are removed on the order of micrometers. [0023] The invention is not limited to the illustrated embodiments. In particular, the configuration of the punched portions can be such that the load-bearing portions are elevated or have other surface patterns. Further thermal coatings may include hypereutectoid aluminum-silicon alloys, carbide-forming coatings, iron alloys, and the like. Finally, the cylinder surface 14 can be precision-machined by laser melting before honing, in which case an intermetallic compound is formed from the materials used. [0024] As a second example, a cylinder block for an internal combustion engine including one sleeve as described above for each cylinder was manufactured from a gray cast iron alloy. The coating of the steel plate sleeve was carried out by flame spraying using an oxygen-containing propellant, but the coating consisted of steel and iron oxide components and exhibited only slight porosity. [0025] In order to improve the frictional characteristics of the cylinder surface, boron nitride was further injected onto the coating film at a volume ratio of 10%. However, excellent results can also be obtained using graphite or MoS2 as the lubricant. [0026] In a third embodiment using a cylinder block made of a light metal and a sleeve provided with a coating film formed by solidifying cast iron as leadebrite after thermal spraying as described above, the above-mentioned coating film is As a second layer covering the
Overcoated with aluminum bronze (Al-3N) below 0°C. This ensured a strong metal-to-metal bond when the sleeve was later bonded to a light metal matrix. [0027]

【Effect of the invention】

By thermally forming a coating on the surface of the sleeve according to the invention before it is inserted into a mold for a cylinder block, two things are achieved. [0028] First, the coating ensures corrosion resistance of the sleeve until the end of casting and improves the frictional properties of the contact surface with the piston. Second, the coating has a certain degree of surface roughness or porosity that improves the bond strength between the sleeve and the base material. During finishing machining (poling and honing) of the contact surface with the piston, the coating film is partially peeled off, but after that, a film of lubricating oil adheres to the part of the contact surface that retains porosity. This provides excellent wear resistance. The thermal conductivity is only slightly impaired compared to the inner surface of a cylinder made of a light metal, such as a hypereutectoid aluminum-silicon alloy.

[Brief explanation of drawings]

1 is a plan view showing only a part of a cylinder block for a multi-cylinder internal combustion engine with a sleeve according to the invention; FIG.

[Figure 2] It is a figure which shows the said sleeve made from a thin steel plate three-dimensionally.

[Figure 3] 3 is a partial end view of the sleeve of FIG. 2; FIG.

[Figure 4] FIG. 3 is a front view partially showing the inner surface of the sleeve of FIG. 2;

[Figure 5] FIG. 2 is a sectional view taken along line v-■ in FIG. 1;

[Figure 6] FIG. 4 is a detailed view of a portion Z in FIG. 3;

[Explanation of symbols]

10 Cylinder block 14　Cylinder inner surface 16 Sleeve 18 Thin section 24 Contact points

[Document base]

drawing

[Figure 1] lθ-cylinder block /4-n9nta “inner side” /6---three

[Figure 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

Claims (1)

[Scope of Claims] [Claim 1] A perforated sleeve made of a material having excellent wear resistance and a relatively high melting point is provided in one cylinder as a part of the inner surface of the cylinder. In the alloy cylinder block for internal combustion engines, the sleeve (16) is made of a thin metal plate with holes formed by punching, and the punched portions are Cylinder block for internal combustion engines, characterized in that it is covered with a layer thermally formed by thermal spraying. 2. According to claim 1, the lamina (18) formed in the punching is oriented so as to deviate from the cross-sectional curvature of the cylinder and cut in the direction of the basic material of the cylinder block. Cylinder block for the internal combustion engine described. 3. The cylinder block for an internal combustion engine according to claim 1, wherein the layer covering the punched portion is a porous layer. [Claim 4] The sleeve (16) is made of a steel plate,
4. Cylinder block for an internal combustion engine according to claim 1, characterized in that the cylinder block is welded at contact points (24) running obliquely to the cylinder axis. 5. The thin pieces (18) formed in the punched portion are positioned at an oblique angle (β) with respect to each other when viewed in the axial direction of the cylinder. The cylinder block for an internal combustion engine according to any one of items 1 to 4. [Claim 6] The sleeve (16) is 0.4 mm to 1.5 mm.
6. Cylinder block for an internal combustion engine according to claim 1, characterized in that it has a wall thickness s of up to mm. Claim 7: The slices (18) of the sleeve (16) are 1-5.
Cylinder block for an internal combustion engine according to one of claims 5 and 6, characterized in that it has a punching depth t of mm, in particular about 3 mm. 8. The angle (α) of the thin piece (18) with respect to the radial direction of the cylinder is from 5° to 75°, particularly from 30° to 60°.
8. The cylinder block for an internal combustion engine according to claim 7, characterized in that the cylinder block is between .degree. 9. Cylinder block for an internal combustion engine according to claim 1, characterized in that the thermally formed layer is a layer of cast iron solidified as ledebrite. 10. A cylinder for an internal combustion engine according to claim 1, wherein the thermally formed layer is a layer of a hypereutectoid aluminum-silicon alloy. block. 11. According to claim 1, the thermally formed coating is made of a ceramic component, in particular Al_2O_3, TiO or ZrO_2. Cylinder block for internal combustion engines. 12. A cylinder for an internal combustion engine according to claim 1, wherein the thermally formed coating is made of high-alloy tool steel. block. 13. The method according to claim 1, wherein the thermally formed coating is made of iron or a mixture of steel and iron oxide. Cylinder block for internal combustion engines. 14. The cylinder block for an internal combustion engine according to claim 9, wherein the coating film contains a self-lubricating compound mixed therein. 15. The cylinder block for an internal combustion engine according to claim 14, wherein the compound comprises at least one of graphite, MoS_2, and boron nitride. 16. The cylinder block for an internal combustion engine according to claim 14, wherein the volume proportion of the compound is from 3 to 15%. Claim 1: The surface of the coating film is further coated with a flux or an alloy having high affinity for the base material. Cylinder block for the internal combustion engine described. 18. The cylinder block for an internal combustion engine according to claim 17, wherein when an aluminum alloy is used as the base material, the cylinder block is coated with aluminum bronze having a melting point of less than 500°C. 19. A) manufacturing one perforated sleeve (16) for each cylinder, b) forming a coating film on the surface of the sleeve by thermal spraying, c) using the sleeve as follows:
19. Any one of claims 1 to 18, characterized in that the cylinder block is fitted into a mold for a cylinder block and adjusted in position, and d) the cylinder block is cast by supplying molten alloy into the mold. A method of manufacturing the cylinder block described in . 20. Claim 20, characterized in that an aluminum-silicon alloy is used for said casting, and that the silicon content of said aluminum-silicon alloy is less than 14%, in particular about 10%. 20. A method for manufacturing a cylinder block according to 19. 21. The method for manufacturing a cylinder block according to claim 19, wherein the cylinder block is cast by a pressure die-gas casting method. 22. The cylinder block according to claim 19, wherein the inner surface of the cylinder is machined, honed and finally brushed after casting of the cylinder block. How to manufacture. 23. From claim 19, characterized in that the inner surface of the cylinder is at least partially melted before honing, in order to form an intermetallic compound consisting of base material, sleeve and coating in the surface area. 22. A method for manufacturing a cylinder block according to any one of items 22 to 22.